Dunham Treatment Including Effects of the Born–Oppenheimer Breakdown for Open-Shell Diatomic Molecules in2Σ States

✍ Scribed by Hiromichi Uehara

• Publisher: Elsevier Science
• Year: 1998
• Tongue: English
• Weight: 179 KB
• Volume: 192
• Category: Article
• ISSN: 0022-2852
• DOI: 10.1006/jmsp.1998.7714

✦ Synopsis

A Dunham treatment of an effective Hamiltonian for diatomic molecules in 2 ⌺ states that includes contributions of the Born-Oppenheimer breakdown has yielded an expression for vibrational-rotational energy by an expansion in powers of (v ϩ

state and k ϭ 0, 1, . . . , j. Analytic expressions for the expansion coefficients Y* ijk vJ provide a potential model appropriate for the spectral fits for molecules in 2 ⌺ states. The expansion coefficients Y* ij0 vJ for the k ϭ 0 terms are exactly the same as the Y* ij vN coefficients given for 1 ⌺ states, the Dunham coefficients Y ij modified by the contributions of the Born-Oppenheimer breakdown, provided that a spin contribution originating from off-diagonal electronic corrections of the electronic part of the spin-orbit interaction can be ignored. Spin-rotation energy is given by the terms with coefficients Y* ijk vJ (k Ն 1). There are no Y* ijk vJ (k Ն 2) terms in the previously known methods of analysis for 2 ⌺ molecules. The present potential model is applied to the reported vibrational-rotational spectra of CaH and all spectral lines of 40 CaH and 40 CaD isotopomers are fitted to a single set of molecular constants simultaneously with significantly smaller standard deviations.